Pattern inspection apparatus

ABSTRACT

A pattern inspection apparatus includes a column to scan a substrate on which a pattern is formed, using multi-beams composed of a plurality of electron beams, a first stage to be able to move up to a first stroke by which an entire surface of an inspection region of the substrate can be irradiated with the multi-beams, a second stage, arranged on the first stage, to be able to move up to a second stroke sufficiently shorter than the first stroke and to place the substrate thereon, and a detector to detect secondary electrons emitted from the substrate because the substrate is irradiated with the multi-beams.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2016-090745 filed on Apr. 28,2016 in Japan, the entire contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION Field of the Invention

Embodiments of the present invention relate generally to a patterninspection apparatus. More specifically, for example, embodiments of thepresent invention relate to an inspection apparatus which inspects apattern by acquiring a secondary electron image of a pattern imageemitted due to irradiation by an electron beam.

Description of Related Art

In recent years, with the advance of high integration and large capacityof large-scale integration (LSI) circuits, the line width (criticaldimension) required for circuits of semiconductor elements is becomingprogressively narrower. Such semiconductor elements are manufactured bycircuit formation of exposing and transferring a pattern onto a wafer bymeans of a reduced projection exposure apparatus known as a stepperwhile using an original or “master” pattern (also called a mask or areticle, hereinafter generically referred to as a mask) with a circuitpattern formed thereon.

Since LSI manufacturing requires a tremendous amount of manufacturingcost, it is crucial to improve its yield. However, as typified by a1-gigabit DRAM (Dynamic Random Access Memory), the scale of patternsconfiguring an LSI has become on the order of nanometers fromsub-microns. In recent years, with miniaturization of dimensions of LSIpatterns formed on a semiconductor wafer, dimension to be detected as apattern defect has become extremely small. Therefore, a patterninspection apparatus for inspecting defects of ultrafine patternstransferred and exposed onto a semiconductor wafer needs to be morehighly accurate. Further, one of major factors that decrease the yieldof the LSI manufacturing is due to pattern defects on the mask used forexposing and transfer printing an ultrafine pattern onto a semiconductorwafer by the photolithography technology. Therefore, a patterninspection apparatus for inspecting defects on a transfer mask used inmanufacturing LSI needs to be more highly accurate.

As an inspection method, there is known a method of comparing an opticalimage obtained by imaging a pattern formed on a substrate (target objector “sample”) such as a semiconductor wafer and a lithography mask at apredetermined magnification by using a magnification optical system withdesign data or an optical image obtained by imaging the same pattern onthe target object. For example, the methods described below are known aspattern inspection methods: the “die-to-die inspection” method thatcompares data of optical images of identical patterns at differentpositions on the same mask; and the “die-to-database inspection” methodthat inputs, into an inspection apparatus, writing data (design patterndata) generated by converting pattern-designed CAD data to a writingapparatus specific format to be input to the writing apparatus when apattern is written on the mask, generates a design image data (referenceimage) based on the input writing data, and compares the generateddesign image with an optical image (serving as measurement data)obtained by imaging the pattern. In such inspection methods for use inthe inspection apparatus, a substrate to be inspected (an inspectionsubstrate or “object” to be examined) is placed on the stage so that alight flux may scan the substrate (target object) as the stage moves inorder to perform an inspection. Specifically, the substrate to beinspected is irradiated with a light flux from the light source throughthe illumination optical system. The light transmitted through theinspection substrate or reflected therefrom forms an image on a sensorthrough the optical system. The image captured by the sensor istransmitted as measurement data to the comparison circuit. Afterperforming positioning between images, the comparison circuit comparesmeasurement data with reference data in accordance with an appropriatealgorithm, and determines that there exists a pattern defect if thecompared data are not identical.

The pattern inspection apparatus described above acquires an opticalimage by irradiating an inspection substrate with a laser beam in orderto capture a transmission image or a reflection image of a patternformed on the substrate. On the other hand, there has been developed aninspection apparatus which acquires a pattern image by irradiating aninspection substrate with multiple electron beams in order to detect asecondary electron corresponding to each beam emitted from the substrate(e.g., refer to Japanese Patent Application Laid-open (JP-A) No.2002-208371). The pattern inspection apparatus using an electronbeam(s), such as multiple electron beams or a single electron beam,scans each small region of the inspection substrate with beams in orderto detect a secondary electron. In that case, a so-called “step andrepeat” operation is performed in which the position of the substrate tobe inspected is fixed during the beam scanning, and then, after thescanning, the substrate to be inspected is moved to a next region. Inpattern inspection, since it is necessary to inspect almost the wholesurface of the substrate to be inspected, the substrate is usuallyplaced on a heavy stage driven by a motor, etc. Then, it is difficult toattenuate such a heavy stage after having been moved. As describedabove, since almost the whole surface of the inspection substrate needsto be inspected, the stage moves through a long stroke. For the stagewhich moves through a long stroke, a large attenuation mechanism isneeded to perform attenuation after the moving. Moreover, in order toattenuate, in a short period of time, the stage being heavy and movingthrough a long stroke, a still larger attenuation mechanism is needed.However, it is difficult to arrange a large attenuation mechanism in alimited space. Therefore, an attenuation mechanism arrangeable in thelimited space is used, but, in such a case, it takes time for staticallysettling (stabilizing) the stage to stop at a position within apredetermined accuracy after the step movement of the stage. Supposingthat the settling time needs 20 ms, for example, there is a problem inthat the time obtained by “the number of times of performingstep-and-repeat movement”×“20 ms” is needed as a useless time duringwhich no actual inspection is performed. While at the same time, it isrequired to reduce the inspection time.

BRIEF SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided apattern inspection apparatus including a column configured to scan asubstrate on which a pattern is formed, using multi-beams composed of aplurality of electron beams, a first stage configured to be able to moveup to a first stroke by which an entire surface of an inspection regionof the substrate can be irradiated with the multi-beams, a second stagearranged on the first stage and configured to be able to move up to asecond stroke sufficiently shorter than the first stroke and to placethe substrate thereon, and a detector configured to detect secondaryelectrons emitted from the substrate because the substrate is irradiatedwith the multi-beams.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual diagram showing a configuration of a patterninspection apparatus according to a first embodiment;

FIG. 2 is a conceptual diagram showing a configuration of a shapingaperture array member according to the first embodiment;

FIG. 3 is a top view conceptual diagram showing a part of a blankingaperture array mechanism according to the first embodiment;

FIG. 4 is a conceptual diagram describing an example of a scanningoperation according to the first embodiment;

FIG. 5 shows an example of an irradiation region of multi-beams and ameasurement pixel according to the first embodiment;

FIG. 6 is a conceptual diagram describing an example of details of ascanning operation according to the first embodiment;

FIG. 7 shows an example of a structure of an image detection mechanismaccording to a comparative example to the first embodiment;

FIG. 8 shows a stage position distribution according to the comparativeexample to the first embodiment;

FIG. 9 is a time chart showing a relation among a main stage position, amicromotion stage position, and a substrate position according to thefirst embodiment;

FIGS. 10A and 10B show examples of a part of structure of an attenuationmechanism according to the first embodiment and a comparative example;

FIG. 11 shows an internal configuration of a comparison circuitaccording to the first embodiment; and

FIG. 12 is a time chart showing a relation among a main stage position,a micromotion stage position, and a substrate position according to asecond embodiment.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the present invention describe a patterninspection apparatus capable of reducing the time during which noinspection can be performed because of the “step and repeat” operation,in pattern inspection using electron beams.

First Embodiment

FIG. 1 is a conceptual diagram showing a configuration of a patterninspection apparatus according to the first embodiment. In FIG. 1, aninspection apparatus 100 for inspecting patterns formed on the substrateis an example of a multi electron beam inspection apparatus. Theinspection apparatus 100 includes an optical image acquisition unit 150and a control system circuit 160 (control unit). The optical imageacquisition unit 150 includes an electron beam column 102 (electronoptical column), an inspection chamber 103, a detection circuit 106, achip pattern memory 123, a stage drive mechanism 142, and laser lengthmeasurement systems 122 and 125. In the electron beam column 102, thereare arranged an electron gun 201, an illumination lens 202, a shapingaperture array member 203, a blanking aperture array mechanism 204, areducing lens 205, a limiting aperture member 206, an objective lens207, a deflector 208, and a plurality of detectors 222 and 224.

In the inspection chamber 103, there is arranged an The XY stage 105which is movable at least in the x-y directions. On the XY stage 105,there are placed a micromotion stage 140 which is movable at least inthe x-y directions, a stage drive mechanism 132 which drives themicromotion stage 140, and an attenuation mechanism 134 which attenuatesthe movement of the micromotion stage 140. Then, on the micromotionstage 140, there is placed a substrate 101 on which a plurality of chippatterns to be inspected are formed. The substrate 101 may be anexposure mask or a semiconductor substrate such as a silicon wafer asdescribed above. The substrate 101 is placed, on the micromotion stage140, with its pattern forming surface facing upward, for example. On themicromotion stage 140, there is placed a mirror 217 which reflects alaser beam for measuring a laser length emitted from the laser lengthmeasurement system 122 arranged outside the inspection chamber 103.Similarly, on the XY stage 105, there is arranged a mirror 216 whichreflects a laser beam for measuring a laser length emitted from thelaser length measurement system 125 arranged outside the inspectionchamber 103. The detectors 222 and 224 are connected, at the outside ofthe electron beam column 102, to the detection circuit 106. Thedetection circuit 106 is connected to the chip pattern memory 123.

In the control system circuit 160, a control computer 110 is connected,through a bus 120, to a position circuit 107, a comparison circuit 108,a development circuit 111, a reference circuit 112, a stage controlcircuit 114, a lens control circuit 124, a blanking control circuit 126,a deflection control circuit 128, a storage device 109 such as amagnetic disk drive, etc., a monitor 117, a memory 118, and a printer119. The chip pattern memory 123 is connected to the comparison circuit108.

The XY stage 105 (first stage) is driven by a stage drive mechanism 130controlled by the stage control circuit 114 under control of the controlcomputer 110. The XY stage 105 (first stage) can move up to a stroke(first stroke) by which all the surface of the inspection region of thesubstrate 101 can be irradiated with multi-beams 20. The XY stage 105can be moved by a drive system such as a three-axis (X, Y, and θ) motor,which drives the stage in the directions of x, y, and θ. For example, astep motor can be used as each of these X, Y, and θ motors (not shown).The XY stage 105 is movable in the horizontal direction and the rotationdirection by the motors of the X-axis, Y-axis, and θ-axis. The movementposition of the XY stage 105 is measured by the laser length measurementsystem 125, and supplied (transmitted) to the position circuit 107. Thelaser length measurement system 125 measures the position (length) ofthe XY stage 105 by receiving a catoptric light from the mirror 216,based on the principle of laser interferometry.

The micromotion stage 140 (second stage) is driven by a stage drivemechanism 132 controlled by the stage control circuit 114 under controlof the control computer 110. The micromotion stage 140 can be moved by adrive system such as a three-axis (X, Y, and θ) motor, which drives thestage in the directions of x, y, and θ. For example, a step motor can beused as each of these X, Y, and θ motors (not shown). The micromotionstage 140 is movable in the horizontal direction and the rotationdirection by the motors of the X-axis, Y-axis, and θ-axis. The movementposition of the micromotion stage 140 is measured by the laser lengthmeasurement system 122, and supplied (transmitted) to the positioncircuit 107. The laser length measurement system 122 measures theposition (length) of the micromotion stage 140 by receiving a catoptriclight from the mirror 217, based on the principle of laserinterferometry.

The micromotion stage 140 (second stage) can move up to a stroke (secondstroke) sufficiently shorter than that of the XY stage 105. If here, thesubstrate 101 is a semiconductor substrate, a plurality of chips eachhaving the same size are formed on the substrate 101 as described later.The stroke of the micromotion stage 140 is, for example, greater than orequal to the size of one chip and less than the size of two chips of aplurality of chips formed on the substrate 101. The micromotion stage140 (second stage) should be a size to be placed on the substrate 101,and can be lighter than the XY stage 105. Since the micromotion stage140 moves a stroke distance greater than or equal to the size of onechip and less than the size of two chips, that is sufficiently short,the attenuation mechanism 134 which provides attenuation in a short timecan be small and simple. Although, in the example of FIG. 1, theattenuation mechanism 134 is arranged between the micromotion stage 140and the XY stage 105, it is not limited thereto. For example, it is alsopreferable that the attenuation mechanism 134 is mounted in the stagedrive mechanism 132, etc.

A plurality of detectors 222 and 224 are arranged above the XY stage 105in a manner such that they surround the optical path of multi-beams tobe described later, and each of their detection surfaces faces theintersection between the surface of the substrate 101 arranged on the XYstage 105 and the optical axis. For example, each of their detectionsurfaces is arranged to be inclined with respect to the surface of thesubstrate 101, which is arranged on the micromotion stage 140 (and theXY stage 105), at an angle from 15° to 75°, for example. Morepreferably, each of the detection surfaces is arranged to be inclined atan angle between 30° and 60°, for example, an angle 45°.

Although, here, the two detectors 222 and 224 are shown as an example,it is not limited thereto, and more detectors may further be arranged.In the case of arranging the two detectors 222 and 224, it is preferablethat they are arranged at positions opposite each other with respect tothe optical path of multi-beams, or at the positions each rotated by 90°about the optical axis of multi-beams as a fulcrum. Moreover, aplurality of detectors 222 and 224 are arranged to be stationaryrelative to the electron beam column 102.

A high voltage power supply circuit (not shown) is connected to theelectron gun 201. The high voltage power supply circuit applies anacceleration voltage to between the cathode and the anode (not shown) inthe electron gun 201. In addition to this applied acceleration voltage,by applying a predetermined bias voltage, and heating the cathode at apredetermined temperature, electrons emitted from the cathode areaccelerated to become electron beams which are to be emitted. Forexample, electron lenses are used as the illumination lens 202, thereducing lens 205, and the objective lens 207, and all of them arecontrolled by the lens control circuit 124. In the blanking aperturearray mechanism 204, a plurality of individual blanking mechanisms arearranged on the blanking substrate to be described later, and a controlsignal to each individual blanking mechanism is output from the blankingcontrol circuit 126. The deflector 208 is configured by at least fourelectrodes, and controlled by the deflection control circuit 128.

In the case of the substrate 101 being a semiconductor wafer on which aplurality of chip (die) patterns are formed, pattern data of the chip(die) pattern is input from the outside the inspection apparatus 100 tothe storage device 109 to be stored therein.

FIG. 1 shows configuration elements necessary for describing the firstembodiment. It should be understood that other configuration elementsgenerally necessary for the writing apparatus 100 may also be includedtherein.

FIG. 2 is a conceptual diagram showing a configuration of a shapingaperture array member according to the first embodiment. As shown inFIG. 2, holes (openings) 22 of n columns wide (x direction) and m rowslong (y direction) are two-dimensionally formed, like a matrix, at apredetermined arrangement pitch in the shaping aperture array member203, where one of n and m is an integer of 1 or more, and the other isan integer of 2 or more. In FIG. 2, for example, holes 22 of 32 (columnsin x direction)×32 (rows in y direction) are formed. Each of the holes22 is a quadrangle of the same dimensional shape. Alternatively, each ofthe holes 22 can be a circle of the same circumference. Multi-beams 20are formed by letting portions of an electron beam 200 individually passthrough a corresponding hole of a plurality of holes 22. Here, the casein which the holes 22 of two or more rows and columns are arranged inboth the x and y directions is shown, but the arrangement is not limitedthereto. For example, it is also acceptable that a plurality of holes 22are arranged in only one row (x direction) or in only one column (ydirection). That is, in the case of only one row, a plurality of holes22 are arranged in the x direction as a plurality of columns, and in thecase of only one column, a plurality of holes 22 are arranged in the ydirection as a plurality of rows. The method of arranging the holes 22is not limited to the case of FIG. 2 where holes are arranged like agrid in the width and length directions. For example, with respect tothe k-th and the (k+1)th rows arrayed in the length direction (ydirection), each hole in the k-th row and each hole in the (k+1)th rowmay be mutually displaced in the width direction (x direction) by adimension “a”. Similarly, with respect to the (k+1)th and the (k+2)throws arrayed in the length direction (y direction), each hole in the(k+1)th row and each hole in the (k+2)th row may be mutually displacedin the width direction (x direction) by a dimension “b”. Alternatively,other configuration may be employed.

FIG. 3 is a top view conceptual diagram showing apart of a blankingaperture array mechanism according to the first embodiment. In FIG. 3,the positional relation of electrodes 24 and 26, and that of a controlcircuit 41 are not in accordance with each other. As shown in FIG. 3, inthe blanking aperture array mechanism 204, there are formed passageholes 25 (openings), through which multiple beams individually pass, atthe positions each corresponding to each hole 22 of the shaping aperturearray member 203 of FIG. 2, on a substrate (not shown) (e.g., siliconsubstrate). Then, a pair of electrodes 24 and 26 (blanker: blankingdeflector) for blanking deflection is arranged close to each passagehole 25 on the substrate in a manner such that the electrodes 24 and 26are opposite each other with respect to the passage hole 25 concerned.Moreover, close to each passage hole 25, there is arranged the controlcircuit 41 (logic circuit) for applying a deflection voltage to, forexample, the electrode 24 for each passage hole 25. The other one (theelectrode 26, for example) of the two electrodes 24 and 26 for each beamis grounded (earthed). Further, a several (e.g., 5 to 10) bit line forcontrol signal is connected to each control circuit 41. In addition tothe several bit line, for example, a clock signal line, a power sourceline, and the like are connected to each control circuit 41. Anindividual blanking mechanism 47 composed of the electrodes 24 and 26and the control circuit 41 is configured for each beam of multi-beams. Acontrol signal for each control circuit 41 is output from the blankingcontrol circuit 126. Moreover, a shift register (not shown) is arrangedin each control circuit 41, and for example, shift registers for beamsin one row of n×m multi-beams in the control circuit are connected inseries. For example, control signals for beams in one row of n×mmulti-beams are transmitted in series. For example, a control signal ofeach beam is stored in a corresponding control circuit 41 by n clocksignals.

The electron beam 20 passing through a corresponding passage hole isindependently deflected by a voltage applied to the two electrodes 24and 26 being a pair. Blanking control is performed by this deflection.Blanking deflection is performed for each corresponding beam ofmulti-beams. Thus, each of a plurality of blankers performs blankingdeflection of a corresponding beam of the multi-beams having passedthrough a plurality of holes 22 (openings) of the shaping aperture arraymember 203. By performing individual blanking control, an extraordinarybeam can be excluded from the inspection.

Although the individual blanking mechanism 47 is shown in the example ofFIG. 3, it is not limited thereto. A mechanism which collectivelyprovide blanking control of the multi-beams 20 may also be employed.

Next, operations of the optical image acquisition unit 150 in theinspection apparatus 100 will be described. The electron beam 200emitted from the electron gun 201 (emission unit) almost perpendicularly(e.g., vertically) illuminates the whole of the shaping aperture arraymember 203 by the illumination lens 202. A plurality of quadrangularholes (openings) are formed in the shaping aperture array member 203.The region including all the plurality of holes is irradiated with theelectron beam 200. For example, a plurality of quadrangular electronbeams (multi-beams) 20 a to 20 e are formed by letting portions of theelectron beam 200, which irradiates the positions of a plurality ofholes 22, individually pass through a corresponding hole of theplurality of holes of the shaping aperture array member 203. Themulti-beams 20 a to 20 e individually pass through correspondingblankers (first deflector: individual blanking mechanism) of theblanking aperture array mechanism 204. Each blanker deflects (providesblanking deflection) the electron beam 20 which is individually passing.

The multi-beams 20 a to 20 e having passed through the blanking aperturearray mechanism 204 are reduced by the reducing lens 205, and go towardthe hole in the center of the limiting aperture member 206. At thisstage, the electron beam 20 which was deflected by the blanker of theblanking aperture array mechanism 204 deviates (shifts) from the hole inthe center of the limiting aperture member 206 and is blocked by thelimiting aperture member 206. On the other hand, the electron beam 20which was not deflected by the blanker of the blanking aperture arraymechanism 204 passes through the hole in the center of the limitingaperture member 206 as shown in FIG. 1. Blanking control is provided byON/OFF of the individual blanking mechanism so as to control ON/OFF ofbeams. Thus, the limiting aperture member 206 blocks each beam which wasdeflected to be in the OFF state by the individual blanking mechanism.Then, for each beam, one shot beam is formed by a beam which has beenmade during a period from becoming beam ON to becoming beam OFF and haspassed through the limiting aperture member 206. The multi-beams 20having passed through the limiting aperture member 206 are focused bythe objective lens 207 so as to be a pattern image of a desiredreduction ratio. Then, respective beams (the whole of the multi-beams20) having passed through the limiting aperture member 206 arecollectively deflected in the same direction by the deflector 208 inorder to irradiate respective beam irradiation positions on thesubstrate 101. Ideally, the multi-beams 20 irradiating at a time arealigned at pitches obtained by multiplying the arrangement pitch of aplurality of holes of the shaping aperture array member 203 by a desiredreduction ratio described above. Thus, the electron beam column 102irradiates the substrate 101 with two-dimensional n×m multi-beams 20 ata time. Secondary electrons 300 being a flux of secondary electronscorresponding to each beam of the multi-beams 20, emitted from thesubstrate 101 because the multi-beams 20 irradiate desired positions ofthe substrate 101, are detected when being incident to a plurality ofdetectors 222 and 224. In other words, for each beam of the multi-beams20, a plurality of detectors 222 and 224 detect secondary electrons 300emitted from one position of the substrate 101, which is irradiated withone beam. Thereby, the information amount of detected data of eachposition of the substrate 101 can be increased.

FIG. 4 is a conceptual diagram describing an example of a scanningoperation according to the first embodiment. As shown in FIG. 4, in aninspection region 30 of the substrate 101, there are formed a pluralityof chips 32 (die) in an array, each having predetermined width andlength in the x and y directions, for example. Each chip 32 is formed tobe, for example, 30 mm×25 mm on the substrate 101. Pattern inspection isperformed for each chip 32. For example, the region of each chip 32 isvirtually divided into a plurality of unit inspection regions 33 by thewidth (x direction) and the length (y direction) being the same as thewidth and length of an irradiation region 34 which can be irradiatedwith one irradiation of the entire multi-beams 20. First, the XY stage105 is moved to make an adjustment so that the irradiation region 34,which can be irradiated with one irradiation of the entire multi-beams20, may be located at the position of the unit inspection region 33 atone (e.g., upper left end) of the four corners of the first chip 32, andthen, a scanning operation is started. According to the firstembodiment, for example, by repeating a “step and repeat” operation,each unit inspection region 33 is scanned by the multi-beams 20 whilethe irradiation region 34 is shifted one by one in the x direction bythe width of the irradiation region 34. After scanning all the unitinspection regions 33 aligned in the x direction in the same row, wherethe rows are arrayed in the y direction, the stage position is moved inthe y direction to similarly scan the unit inspection regions 33 alignedin the x direction in a next row, being the next in the y direction, bythe multi-beams 20. This operation is repeated until scanning the regionof one chip 32 is completed. Then, the XY stage 105 is moved to make anadjustment so that the irradiation region 34, which can be irradiatedwith one irradiation of the entire multi-beams 20, may be located at theposition of the unit inspection region 33 at one (e.g., upper left end)of the four corners of the next chip 32, and then, another scanningoperation is similarly performed. By repeating this operation, all thechips 32 can be scanned.

FIG. 5 shows an example of an irradiation region of multi-beams and ameasurement pixel according to the first embodiment. In FIG. 5, theregion of the chip 32 is divided into a plurality of mesh regions by thebeam size of multi-beams, for example. Each mesh region serves as ameasurement pixel 36 (unit irradiation region). In the irradiationregion 34, there are shown a plurality of measurement pixels 28(irradiation positions of beams of one shot) which can be irradiatedwith one irradiation of the multi-beams 20. In other words, the pitchbetween the adjacent measurement pixels 28 is a pitch P between beams ofthe multi-beams. In the example of FIG. 5, one grid 29 is a squareregion surrounded at four corners by four adjacent measurement pixels28, and including one of the four measurement pixels 28. In the exampleof FIG. 5, each grid 29 is configured by 4×4 pixels.

FIG. 6 is a conceptual diagram describing an example of details of ascanning operation according to the first embodiment. FIG. 6 shows anexample of scanning a certain unit inspection region 33 (irradiationregion 34). In one irradiation region 34, there are arranged n₁×m₁ grids29 in the x and y directions (two-dimensionally). When all the n×mmulti-beams 20 are used, n₁×m₁ grids 29 indicate n×m grids 29. When theXY stage 105 is moved to a position where one unit inspection region 33can be irradiated with the multi-beams 20, the XY stage 105 is stoppedat the position, and then, the inside of the unit inspection region 33concerned is scanned while regarding the unit inspection region 33concerned as the irradiation region 34. Each beam of the multi-beams 20takes charge of one grid 29 different from others. At the time of eachshot, each beam irradiates one measurement pixel 28 equivalent to thesame position in the grid 29 concerned. In the case of FIG. 6, the firstshot of each beam irradiates the first measurement pixel 36 from theright in the bottom row in the grid 29 concerned. Then, the beamdeflection position is shifted in the y direction by one measurementpixel 36 by collectively deflecting the entire multi-beams 20 by thedeflector 208, the second shot irradiates the first measurement pixel 36from the right in the second row from the bottom in the grid 29concerned. Similarly, the third shot irradiates the first measurementpixel 36 from the right in the third row from the bottom in the grid 29concerned. The fourth shot irradiates the first measurement pixel 36from the right in the fourth row from the bottom in the grid 29concerned. Next, the beam deflection position is shifted to the positionof the second measurement pixel 36 from the right in the bottom row bycollectively deflecting the entire multi-beams 20 by the deflector 208,the measurement pixel 36 is similarly irradiated in order in the ydirection. By repeating this operation, all the measurement pixels 36 inone grid 29 are irradiated in order with one beam. In a one-time shot,the secondary electrons 300 being a flux of secondary electronscorresponding to a plurality of shots whose number is at maximum thesame as that of a plurality of holes 22 are detected at a time by themulti-beams formed by passing through the plurality of holes 22 of theshaping aperture array member 203.

As described above, the electron beam column 102 scans the substrate 101on which patterns are formed, by using the multi-beams 20 configured bya plurality of electron beams. The entire multi-beams 20 scans the unitinspection region 33 as the irradiation region 34, and i.e. each beamindividually scans one corresponding grid 29. In a state where the XYstage 105 remains stopped, after scanning one unit inspection region 33is completed, the irradiation region 34 moves to a next adjoining unitinspection region 33 by the step operation in order to scan the nextadjoining unit inspection region 33 while the XY stage 105 remainsstopped. Thus, the “step and repeat” operation is repeated to proceed toscan each chip 32. Due to shot of multi-beams, the secondary electrons300 are emitted, at each time of the shot, circumferentially upward fromthe irradiated measurement pixel 36 so as to be detected by a pluralityof detectors 222 and 224. Each of the plurality of detectors 222 and 224detects, for each measurement pixel 36 (or each grid 29), the secondaryelectrons 300 emitted in the same direction in the secondary electrons300 emitted circumferentially upward from each irradiated measurementpixel 36.

By performing scanning using the multi-beams 20 as described above, thescanning operation (measurement) can be performed at a higher speed thanscanning by a single beam.

Although beam ON/OFF is performed for each 36 in the example describedabove, it is not limited thereto. Scanning may be performed, for eachgrid 29, by continuous beam while the grid 29 concerned is scanned by acorresponding beam. In other words, it may be beam OFF during the stepoperation.

FIG. 7 shows an example of a structure of an image detection mechanismaccording to a comparative example to the first embodiment. In FIG. 7, astage 305 is arranged on the base, and the stage 305 is moved inaccordance with a “step and repeat” operation by a stage drive device342. The position of the stage 305 is measured by a laser interferometer332 which uses a mirror 312 on the stage 305. A column 302 irradiates asubstrate 301 to be inspected on the stage 305 with an electron beamwhile the stage 305 remains stopped, and an image detector 322 detects asecondary electron from the substrate 301 to be inspected.

FIG. 8 shows a stage position distribution according to the comparativeexample to the first embodiment. As described above, the inspectionsubstrate 301 of the comparative example to the first embodiment isarranged on the heavy stage 305. Moreover, as described above, sincealmost the whole surface of the inspection substrate 301 needs to beinspected, the stage 305 moves through along stroke. With respect to thestage 305 being heavy and moving a long stroke distance, it takes timefor statically settling (stabilizing) the stage 305 to stop at aposition within a predetermined accuracy after the step movement of thestage as shown in FIG. 8. Therefore, as described above, there is aproblem in the comparative example in that the time obtained by “thenumber of times of step-and-repeat movement”×“settling time” is neededas a useless time during which no actual inspection is performed. Then,according to the first embodiment, using the micromotion stage 140, itoperates as follows:

FIG. 9 is a time chart showing a relation among a main stage position, amicromotion stage position, and a substrate position according to thefirst embodiment. In FIG. 9, the stage drive mechanism 142 (first stagedrive mechanism) continuously moves the XY stage 105 (main stage) in astep direction (e.g., −x direction) at a constant speed. In a statewhere the micromotion stage 140 remains stopped, the XY stage 105 iscontinuously moved to the position where the irradiation region 34 ofthe multi-beams 20 becomes overlapped with the first unit inspectionregion 33 of the chip 32 to be inspected. When the XY stage 105 reachesthe position where the irradiation region 34 of the multi-beams 20becomes overlapped with the first unit inspection region 33 of the chip32 to be inspected, the stage drive mechanism 132 (second stage drivemechanism) relatively moves the micromotion stage 140 in an oppositedirection (e.g., +x direction) to that of the XY stage 105 at the samespeed as that of the XY stage 105 while the XY stage 105 keeps themovement continuously. By this operation, the position of the substrate101 can be apparently stopped with respect to the electron beam column102. In the state where the micromotion stage 140 is relatively moved atthe same speed as that of the XY stage 105, the unit inspection region33 concerned is scanned by the multi-beams 20. This operation continueswhile the unit inspection region 33 concerned is scanned by themulti-beams 20. When scanning the unit inspection region 33 concerned iscompleted, the stage drive mechanism 132 stops the micromotion stage140. Then, in a state where the micromotion stage 140 remains stopped,the XY stage 105 is continuously moved to the position where theirradiation region 34 of the multi-beams 20 becomes overlapped with anext unit inspection region 33, being the next in the step direction(e.g., x direction) of the chip 32 to be inspected. Similarly, when theXY stage 105 reaches the position where the irradiation region 34 of themulti-beams 20 becomes overlapped with the first unit inspection region33 of the chip 32 to be inspected, the micromotion stage 140 isrelatively moved in an opposite direction (e.g., +x direction) to thedirection of the XY stage 105 at the same speed as that of the XY stage105 while the XY stage 105 keeps the movement continuously. By thisoperation, the position of the substrate 101 is apparently stopped withrespect to the electron beam column 102. Then, in the state where themicromotion stage 140 is relatively moved at the same speed as that ofthe XY stage 105, the unit inspection region 33 concerned is scanned bythe multi-beams 20. As described above, while each of a plurality ofunit inspection regions 33 (small region) of the substrate 101 isscanned by the multi-beams 20, the stage drive mechanism 132 relativelymoves the micromotion stage 140 in an opposite direction (e.g., +xdirection) to that of the XY stage 105 so that the position of thesubstrate 101 may not move in the movement direction of the XY stage 105with respect to the electron beam column 102. The micromotion stage 140repeats moving and stopping in an opposite direction to that of the XYstage 105, in the range of the stroke of the micromotion stage 140, onthe XY stage 105 which is moving continuously. Thereby, a scanningoperation by a step and repeat operation can be performed. In otherwords, the substrate 101 is scanned by a step and repeat operation bythe relative movement between the XY stage 105 and the micromotion stage140 while the XY stage 105 is continuously moving.

As described above, the stroke of the micromotion stage 140 is, forexample, greater than or equal to the size of one chip and less than thesize of two chips of a plurality of chips 32 formed on the substrate101. Therefore, the movement during scanning the unit inspection regions33 aligned in the step direction of the same chip 32 can be within therange of the stroke of the micromotion stage 140. Since the XY stage 105does not stop during that time, it is possible to eliminate the settling(stabilization) time for stopping the XY stage 105 shown in FIG. 8. Onthe other hand, since the micromotion stage 140 is lighter in weightthan the XY stage 105, and its stroke is sufficiently shorter than thatof the XY stage 105, the settling time for stopping the micromotionstage 140 can be short enough to be disregarded compared with that ofthe XY stage 105. Therefore, it is possible to eliminate or greatlyreduce a settling time being a useless time during which no actualinspection is performed. Further, since the unit inspection regions 33aligned in the step direction of the same chip 32 can be scanned withinthe range of the stroke of the micromotion stage 140, generation ofpositional deviation due to stopping of the XY stage 105, etc. can beavoided. Therefore, inspection of the unit inspection regions 33 alignedin the step direction of the same chip 32 can be performed under thesame conditions.

Then, when scanning of all the unit inspecting regions 33 aligned in thestep direction of the inspection chip 32 is completed, the XY stage 105is stopped, and then, moved so that the unit inspection region 33 to befirst scanned in a next row, being the next in the y direction, mayoverlap with the irradiation region 34. While moving the XY stage 105,the stage drive mechanism 132 moves the micromotion stage 140 in anopposite direction (this time, −x direction) to reset the position ofthe micromotion stage 140 in order to prepare starting a next strokemovement. Thereby, the reset time of the micromotion stage 140 can beoverlapped with the movement time of the XY stage 105. When theirradiation region 34 of the multi-beams 20 has moved to the positionoverlapping with the first unit inspection region 33 in a next row,being the next in the y direction of the chip 32, the same operation asdescribed above will be performed. By repeating the operation describedabove, scanning all the unit inspecting regions 33 of one chip 32 can beperformed.

When scanning the chip 32 to be inspected is completed, the scanningoperation is similarly performed for a next chip 32, which should berepeated until all the chips have been scanned.

FIGS. 10A and 10B show examples of apart of structure of an attenuationmechanism according to the first embodiment and a comparative example.FIG. 10A shows, as a comparative example to the first embodiment, thecase where an attenuation mechanism 334 is arranged at the lower part,etc. of the stage 305 shown in FIG. 7. A viscous fluid 15 is enclosed ina case 13, and a movable body 11 connected to the stage 305 is arranged,with some space to the wall of the case 13, in the viscous fluid 15. Themovable body 11 is large in order to attenuate the heavy stage 305, andthe amount of the viscous fluid 15 is also large. Further, from thenecessity of putting the entire surface of the inspection substratewithin the beam irradiation region, a movement stroke S1 of the stage305 is long, and therefore, the amount of the viscous fluid 15 is allthe more large. Thus, the attenuation mechanism 334 becomes large insize. On the other hand, the micromotion stage 140 according to thefirst embodiment can be sufficiently lighter in weight than the XY stage105, and the size of a movable body 10 arranged, with some space to thewall of a case 12, in a viscous fluid 14 can be small as shown in FIG.10B. Besides, since a movement stroke S2 of the micromotion stage 140 issufficiently small, the amount of the viscous fluid 14 to be enclosed inthe case 12 can be small. Thus, the attenuation mechanism 134 can besmall in size. Therefore, it is possible to arrange, even in a limitedspace, the attenuation mechanism 134 that can be effective insufficiently attenuating the micromotion stage 140 in a short time.Accordingly, the settling time for stopping the micromotion stage 140can be short enough to be disregarded compared with that of the XY stage105.

In a step of multi-beam scanning and a secondary electron detecting, asdescribed above, the optical image acquisition unit 150, using themulti-beams 20 in which a plurality of electron beams are arranged at apredetermined pitch P, scans the inspection substrate 101 on which aplurality of figure patterns are formed, and detects the secondaryelectrons 300 emitted from the irradiated inspection substrate 101 dueto irradiation with the multi-beams 20. The method for scanning and themethod for detecting the secondary electrons 300 have already beendescribed above. Detected data on the secondary electrons 300 from eachmeasurement pixel 36 detected by the detectors 222 and 224 is output tothe detection circuit 106 in order of measurement. In the detectioncircuit 106, the detected data in analog form is converted into digitaldata by an A-D converter (not shown), and stored in the chip patternmemory 123. Then, at the stage when detected data for one chip 32 hasbeen accumulated, the accumulated detected data is transmitted as chippattern data to the comparison circuit 108, with information on eachposition from the position circuit 107.

On the other hand, in parallel or in tandem with the step of multi-beamscanning and the secondary electron detecting, a reference image isformed (generated).

In a reference image generation step, if the substrate 101 is asemiconductor substrate, a reference image generation unit, such as thedevelopment circuit 111 and the reference circuit 112, generates areference image of a region corresponding to a measurement image(optical image) of the grid 29 configured by a plurality of pixels 36,based on exposure image data defining an exposure image on the substrateused when a mask pattern of an exposure mask is exposed and transferredonto the semiconductor substrate. Instead of the exposure image data,writing data (design data) may be used which is base for forming anexposure mask to expose and transfer a plurality of figure patterns ontothe substrate 101. If the substrate 101 is an exposure mask, thereference image generation unit, such as the development circuit 111 andthe reference circuit 112, generates a reference image of a regioncorresponding to a measurement image (optical image) of the grid 29configured by a plurality of pixels 36, based on writing data (designdata) which is base for forming a plurality of figure patterns on thesubstrate 101. An optical image may be generated by making itsresolution lower than that of an image in units of grids 29, as an imagein units of unit inspection regions 33 in which one grid 29 is onepixel. In such a case, a reference image can be similarly generated bymaking its resolution lower than that of an image in units of grids 29,as an image in units of unit inspection regions 33 in which one grid 29is one pixel. In the case of the grid 29 being one pixel, the patternoccupancy in the grid 29 can be a gray scale value.

Specifically, it operates as follows: First, the development circuit 111reads writing data (or exposure image data) from the storage device 109through the control computer 110, converts each figure pattern of eachirradiation region 34 defined in the read writing data (or exposureimage data) into image data of binary values or multiple values, andtransmits this image data to the reference circuit 112.

Here, basics of figures defined by writing data (or exposure image data)are, for example, rectangles or triangles. For example, there is storedfigure data defining the shape, size, position, and the like of eachpattern figure by using information, such as coordinates (x, y) of thereference position of the figure, lengths of sides of the figure, and afigure code serving as an identifier for identifying the figure typesuch as a rectangle, a triangle and the like.

When writing data (or exposure image data) used as figure data is inputto the development circuit 111, the data is developed into data of eachfigure. Then, figure codes, figure dimensions and the like indicatingfigure shapes in the figure data are interpreted. Then, the developmentcircuit 111 develops design image data of binary values or multiplevalues, as a pattern to be arranged in a square in units of grids ofpredetermined quantization dimensions, and outputs the developed data.In other words, the development circuit 111 reads design data,calculates the occupancy rate occupied by figures in a design patternfor each square obtained by virtually dividing an inspection region intosquares in units of predetermined dimensions, and outputs n-bitoccupancy rate data. For example, it is preferable that one square isset as one pixel. If one pixel has a resolution of 1/2⁸ (=1/256), 1/256small regions, whose number is the same as that of figure regionsarranged in a pixel, are allocated in order to calculate the occupancyrate in the pixel. Then, the calculated rate is output as 8-bitoccupancy rate data to the reference circuit 112. The size of the squarecan preferably be the same as that of the measurement pixel 36. If thegrid 29 is one pixel, the square size may be the same as that of thegrid 29.

The reference circuit 112 performs appropriate filter processing ondesign image data being transmitted image data of a figure. Since themeasurement data as an optical image obtained from the detection circuit106 is in the state affected by the filtering by the electron opticalsystem, in other words, in the analog state continuously changing, it ispossible to match the design image data with the measurement data byalso performing filter processing on the design image data being imagedata on the design side whose image intensity (gray value) isrepresented by digital values. In this manner, a design image (referenceimage) to be compared with a measurement image (optical image) of thegrid 29 is generated. The generated image data of the reference image isinput into the comparison circuit 108 to be stored in the memory.

FIG. 11 shows an internal configuration of a comparison circuitaccording to the first embodiment. In FIG. 11, storage devices 50 and52, such as magnetic disk drives, a combining unit 54, an alignment unit58, and a comparison unit 60 are arranged in the comparison circuit 108.Each of the “units” such as the combining unit 54, the alignment unit58, and the comparison unit 60 includes a processing circuitry. As theprocessing circuitry, for example, an electric circuit, computer,processor, circuit board, quantum circuit, or semiconductor device maybe used. Each of the “units” may use a common processing circuitry (sameprocessing circuitry), or different processing circuitries (separateprocessing circuitries). Input data required in the combining unit 54,the alignment unit 58, and the comparison unit 60, and calculatedresults are stored in a memory (not shown) each time.

Chip pattern data transmitted from each of the detectors 222 and 224 istemporarily stored in the storage device 50, with information indicatingeach position from the position circuit 107. Similarly, reference imagedata is temporarily stored in the storage device 52, with informationindicating each design position. According to the first embodiment, aplurality of detectors 222 and 224 detect the secondary electrons 300emitted from the same position on the substrate 101. Then, the combiningunit 54 (image generation unit) combines each data detected by aplurality of detectors 222 and 224, and generates an image of a pattern.By using a plurality of detectors, the amount of information is largerthan that of data detected by a single detector, and therefore, a highlyprecise two-dimensional image can be generated. Alternatively, since theamount of information is large, a three-dimensional image may begenerated. When an optical image is a three-dimensional image, areference image should also be a three-dimensional image.

Next, the alignment unit 58 provides positioning between an opticalimage (measurement image) and a reference image, using units of subpixels each smaller than the pixel 36. For example, positioning may beperformed by a least-square method.

The comparison unit 60 compares the optical image concerned and thereference image for each pixel 36. The comparison unit 60 compares boththe images for each pixel 36, based on predetermined determinationconditions in order to determine whether there is a defect, such as ashape defect. For example, if a gradation value difference of each pixel36 is larger than a determination threshold Th, it is determined thatthere is a defect. Then, the comparison result is output, andspecifically, output to the storage device 109, monitor 117, or memory118, or alternatively, output from the printer 119. In the case of thegrid 29 being a pixel, the pixel 36 should be read as the grid 29.

As described above, according to the first embodiment, it is possible inpattern inspection using electron beams to reduce the time in whichinspection cannot be performed because of the “step and repeat”operation. Therefore, inspection time can be shortened.

Second Embodiment

In the first embodiment, there has been described a method for producinga step and repeat operation by adjustment of the micromotion stage 140while continuously moving the XY stage 105 at a constant speed, but theoperation method is not limited thereto. In the second embodiment,another operation method will be described. The configuration of theinspection apparatus 100 is the same as that of FIG. 1. The contents ofthe present embodiment are the same as those of the first embodimentexcept for the operation method of the XY stage 105 and the micromotionstage 140.

FIG. 12 is a time chart showing a relation among a main stage position,a micromotion stage position, and a substrate position according to thesecond embodiment. In FIG. 12, in a state where the micromotion stage140 remains stopped, the stage drive mechanism 142 (first stage drivemechanism) moves the XY stage 105 (first stage) to the position wherethe irradiation region 34 of the multi-beams 20 becomes overlapped withthe first unit inspection region 33 of the chip 32 to be inspected, andthen stops the XY stage 105. When the XY stage 105 reaches the positionwhere the irradiation region 34 of the multi-beams 20 becomes overlappedwith the first unit inspection region 33 of the chip 32 to be inspected,while the XY stage 105 and the micromotion stage 140 remain stopped, theunit inspection region 33 concerned is scanned by the multi-beams 20.When scanning the unit inspection region 33 concerned is completed, in astate in which the XY stage 105 is stopped, the stage drive mechanism132 (second stage drive mechanism) moves the micromotion stage 140 inthe −x direction to the position where the irradiation region 34 of themulti-beams 20 becomes overlapped with a next unit inspection region 33,being the next in the step direction (e.g., x direction), and then stopsthe micromotion stage 140. When the micromotion stage 140 reaches theposition where the irradiation region 34 of the multi-beams 20 becomesoverlapped with the unit inspection region 33 concerned, while the XYstage 105 and the micromotion stage 140 remain stopped, the unitinspection region 33 concerned is scanned by the multi-beams 20. Whenscanning the unit inspection region 33 concerned is completed, while theXY stage 105 remains stopped, the stage drive mechanism 132 (secondstage drive mechanism) moves the micromotion stage 140 in the −xdirection to the position where the irradiation region 34 of themulti-beams 20 becomes overlapped with a next unit inspection region 33,being further next in the step direction (e.g., x direction), and then,stops the micromotion stage 140. When the micromotion stage 140 reachesthe position where the irradiation region 34 of the multi-beams 20becomes overlapped with the unit inspection region 33 concerned, whilethe XY stage 105 and the micromotion stage 140 remain stopped, the unitinspection region 33 concerned is scanned by the multi-beams 20. Themicromotion stage 140 is made to repeat moving and stopping in the rangeof the stroke (second stroke) of the micromotion stage 140. As describedabove, the stage drive mechanism 132 makes the micromotion stage 140repeat moving and stopping in a predetermined direction in the range ofthe stroke of the micromotion stage 140 while the XY stage 105 remainsstopped so that each of a plurality of unit inspection regions 33 of thesubstrate 101 may be scanned by the multi-beams 20. Thereby, a scanningoperation by a step and repeat operation can be performed.

As described above, the stroke of the micromotion stage 140 is, forexample, greater than or equal to the size of one chip and less than thesize of two chips of a plurality of chips 32 formed on the substrate101. Therefore, the movement during scanning the unit inspection regions33 aligned in the step direction of the same chip 32 can be within therange of the stroke of the micromotion stage 140. Since the XY stage 105does not stop during that time, it is possible to eliminate the settling(stabilization) time for stopping the XY stage 105 shown in FIG. 8. Onthe other hand, since the micromotion stage 140 is lighter in weightthan the XY stage 105, and its stroke is sufficiently shorter than thatof the XY stage 105, the settling time for stopping the micromotionstage 140 can be short enough to be disregarded compared with that ofthe XY stage 105. Therefore, it is possible to eliminate or greatlyreduce a settling time being a useless time during which no actualinspection is performed. Further, since the unit inspection regions 33aligned in the step direction of the same chip 32 can be scanned withinthe range of the stroke of the micromotion stage 140, generation ofpositional deviation due to stopping of the XY stage 105, etc. can beavoided. Therefore, inspection of the unit inspection regions 33 alignedin the step direction of the same chip 32 can be performed under thesame conditions.

Then, when scanning of all the unit inspecting regions 33 aligned in thestep direction of the inspection chip 32 is completed, the XY stage 105is moved so that the unit inspection region 33 to be first scanned in anext row, being the next in the y direction, may overlap with theirradiation region 34. In other words, when it becomes necessary to havean amount exceeding the stroke of the micromotion stage 140 as arelative movement amount of the micromotion stage 140 with respect tothe electron beam column 102, the XY stage 105 is made to move. Then,while the XY stage 105 is moved, the stage drive mechanism 132 moves themicromotion stage 140 in an opposite direction (this time, +x direction)to reset the position of the micromotion stage 140 in order to preparestarting a next stroke movement. In other words, while the XY stage 105is moving, the relative position of the micromotion stage 140 to the XYstage 105 is returned to the original position. Thereby, the reset timeof the micromotion stage 140 can be overlapped with the movement time ofthe XY stage 105. When the irradiation region 34 of the multi-beams 20has moved to the position overlapping with the first unit inspectionregion 33 in a next row, being the next in the y direction, of the chip32 to be inspected, the same operation as described above will beperformed. By repeating the operation described above, scanning all theunit inspecting regions 33 of one chip 32 can be performed.

When scanning the chip 32 to be inspected is completed, the scanningoperation is similarly performed for a next chip 32, which should berepeated until all the chips have been scanned.

As described above, according to the second embodiment, similarly to thefirst embodiment, it is possible in pattern inspection using electronbeams to reduce the time in which inspection cannot be performed becauseof the “step and repeat” operation. Therefore, inspection time can beshortened.

In the above description, each “ . . . circuit” includes a processingcircuitry. As the processing circuitry, for example, an electriccircuit, computer, processor, circuit board, quantum circuit,semiconductor device, or the like can be used. Each “ . . . circuit” mayuse a common processing circuitry (same processing circuitry), ordifferent processing circuitries (separate processing circuitries). Aprogram for causing a computer to execute the processor and the like canbe stored in a recording medium, such as a magnetic disk drive, magnetictape drive, FD, ROM (Read Only Memory), etc.

Embodiments have been explained referring to specific examples describedabove. However, the present invention is not limited to these specificexamples. Although, in the case described above, a plurality ofdetectors 222 and 224 detect the secondary electrons 300 emitted fromthe same position on the substrate 101, it is not limited thereto. Asingle detector may also be used for detection when it is acceptablethat the amount of information on each position on the substrate 101 isdecreased, or when the secondary electrons 300 emitted from the sameposition on the substrate 101 can be loaded in one direction by themagnetic field, electric field, or the like of the optical system.

While the apparatus configuration, control method, and the like notdirectly necessary for explaining the present invention are notdescribed, some or all of them can be selectively used on a case-by-casebasis when needed.

In addition, any other pattern inspection apparatus and method thatinclude elements of the present invention and that can be appropriatelymodified by those skilled in the art are included within the scope ofthe present invention.

Additional advantages and modification will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

What is claimed is:
 1. A pattern inspection apparatus comprising: acolumn configured to scan a substrate on which a pattern is formed,using multi-beams composed of a plurality of electron beams; a firststage configured to be able to move up to a first stroke by which anentire surface of an inspection region of the substrate can beirradiated with the multi-beams; a second stage arranged on the firststage and configured to be able to move up to a second strokesufficiently shorter than the first stroke and to place the substratethereon; and a detector configured to detect secondary electrons emittedfrom the substrate because the substrate is irradiated with themulti-beams.
 2. The apparatus according to claim 1, further comprising:a first stage drive mechanism configured to continuously move the firststage; and a second stage drive mechanism configured, for each of aplurality of small regions of the substrate, to relatively move thesecond stage in a direction opposite to that of the first stage suchthat a position of the substrate does not move in a movement directionof the first stage with respect to the column while a small regionconcerned of the plurality of small regions is scanned by themulti-beams, wherein the second stage repeats moving and stopping in thedirection opposite to that of the first stage, in a range of the secondstroke, on the first stage which moves continuously.
 3. The apparatusaccording to claim 2, wherein a plurality of chips each having a samesize are formed on the substrate, and the second stroke is greater thanor equal to a size of one chip and less than a size of two chips of theplurality of chips formed on the substrate.
 4. The apparatus accordingto claim 1, further comprising: a first stage drive mechanism configuredto move the first stage; and a second stage drive mechanism configured,for each of a plurality of small regions of the substrate, to make thesecond stage repeat moving and stopping in a predetermined direction ina range of the second stroke, while the first stage remains stopped,such that a small region concerned of the plurality of small regions isscanned by the multi-beams, wherein in a case where a relative movementamount of the second stage needs to be an amount exceeding the secondstroke with respect to the column, the first stage is moved, and arelative position of the second stage to the first stage is returned toan original position while the first stage is moving.
 5. The apparatusaccording to claim 4, wherein a plurality of chips each having a samesize are formed on the substrate, and the second stroke is greater thanor equal to a size of one chip and less than a size of two chips of theplurality of chips formed on the substrate.
 6. The apparatus accordingto claim 1, wherein a position of the detector is arranged to bestationary relative to the column.
 7. The apparatus according to claim1, wherein the substrate is irradiated with the multi-beams in a statewhere the substrate remains stopped relative to the column by a relativemovement between the first stage and the second stage.
 8. The apparatusaccording to claim 1, wherein the column includes a deflector, and thesubstrate is scanned by collectively deflecting the multi-beams by thedeflector.
 9. The apparatus according to claim 2, wherein the substrateperforms a step and repeat operation by a relative movement between thefirst stage and the second stage while the first stage is continuouslymoving.
 10. The apparatus according to claim 1, wherein the second stageis sufficiently lighter in weight than the first stage.